Covering for perforated inking drums of stencil printing machines

ABSTRACT

A mimeograph type of duplicating machine is made capable of printing stencils of various sizes by the use of specially constructed overlay or cover members, each of which effectively bars the passage of ink over all areas of an ink reservoir drum larger than the stencil being printed. The overlay member is made of a generally porous cloth with a rubber coating vulcanized to the cloth over all portions thereof except the portion to be covered by a stencil.

United States Patent [191 Vosburg et al.

[ 51 Oct. 29, 1974 COVERING FOR PERFORATED INKING DRUMS OF STENCILPRINTING MACHINES [75] Inventors: Guy M. Vosburg, Park Ridge; John C.Marxen, Arlington Heights, both of 111.

[73] Assignee: Weber Marking Systems, Inc.,

Arlington Heights, 111.

[22] Filed: Nov. 7, 1973 [21] Appl. No.: 413,598

Related US. Application Data [63] Continuation of Ser. No. 224,848, Feb.9, 1972,

abandoned.

[52] US. Cl. 101/116, 101/125 [51] Int. Cl B411 13/04 [58] Field ofSearch l0l/ll6,ll9,l21, 122,

[56] References Cited UNITED STATES PATENTS 1,607,386 11/1926 Brasseur..l0l/l16 1,808,986 6/1931 Hunter 10l/127 2,299,628 10/1942 Johnson etal. lOl/l27 2,429,927 10/1947 Doolittle lOl/ll6 3,483,820 12/1969Schuttenberg lOl/l27.l

Primary Examiner-Robert E. Bagwill Assistant ExaminerR. E. SuterAttorney, Agent, or Firm-Kenneth T. Snow [57] ABSTRACT A mimeograph typeof duplicating machine is made capable of printing stencils of varioussizes by the use of specially constructed overlay or cover members, eachof which effectively bars the passage of ink over all areas of an inkreservoir drum larger than the stencil being printed. The overlay memberis made of a generally porous cloth with a rubber coating vulcanized tothe cloth over all portions thereof except the portion to be covered bya stencil.

1 Claim, 5 Drawing Figures PATENIEDUETZQ m4 3. 844212 III, "I",

COVERING FOR PERFORATED INKING DRUMS OF STENCIL PRINTING MACHINESREFERENCE TO PRIOR APPLICATION This application is a continuation ofapplication Ser. No. 224,848, filed Feb. 9, I972 and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention Mimeograph typestencil duplicating machines generally employ a rotating drum. A majorpart of the cylindrical surface of the drum is provided with closelyspaced apart apertures through which ink supplied to the interiorreservoir of the drum may be expelled radially outwardly in the printingoperation. A precut stencil is wrapped around the drum and held theretowith clamping means usually provided in areas of the drum having noapertures. As the ink moves outwardly it effectively inks the indiciamaterial cut in the stencil and causes a transfer to and a printing ofthe stencil cut indicia on paper pressed thereagainst. Further, a clothor fabric is usually interposed between the drum and the stencil as acushion for the stencil and to gain more uniform ink distribution. Thisinsures that the stencil will be inked over its full surface and notjust at the point of contact with each aperture.

The first such mimeograph type stencil duplicating machines were made toaccommodate the width of a letter or legal size sheet of paper and thelength of the longer legal sheet. Since then machines of this type havebeen specially made to take stencils of post card size and of variousmarking stencil sizes. As a rule though for each size stencil desired tobe printed a correspondingly sized machine has been made. Shielding orblocking portions of an apertured drum in prior devices to print asmaller stencil has been extremely difficult and rather impractical atleast insofar as width is concerned.

2. Description of the Prior Art A search has failed to produce anyspecific overlay or covering constructions similar to applicants novelcover. The patent to Kvarnegard U.S. Pat. No. 2,604,847 describes aduplicating machine drum having means to secure a block-out sheetthereto, but such a block-out sheet is not further defined. It wouldappear the Kvarnegard block-out sheet would be a continuous sheet andnot one with various size openings therein.

The patent to Ritzerfeld et al. U.S. Pat. No. 3,220,342 employs twoseparate spaced apart overlay sheets which are stated to bestrategically positioned over the drum to expose more or less of theprinting drum.

SUMMARY OF THE INVENTION The present invention relates to a new andimproved overlay sheet for the perforated drums of stencil duplicatingmachines.

It is a principal object of this invention to provide an overlay for theapertured printing drums of stencil duplicating machines which isbasically a porous fabric having portions made impervious to the passageof ink by a synthetic rubber covering vulcanized thereto.

An important object of this invention is to provide a covering for theperforated ink dispensing drums of stencil duplicating machines whichperforms the several functions of forming a cushioned base for theoverlying stencil, dispersing the ink over surfaces not directly inalignment with the drum apertures and barring the passage of ink overother surfaces of the drum not covered by a stencil.

A further important object of this invention is to provide a coveringfor the perforated ink dispensing drums of stencil duplicating machineshaving a base porous fabric and an ink impervious coating fastened toselected portions thereof.

Another important object of this invention is to provide a covering foran ink dispensing perforated drum which comprises a fabric with a smoothside and a nap side and an ink impervious rubber coating vulcanized toselected portions of the nap side.

Another and further important object of this invention is to provide acovering as defined in the preceding object in which the smooth side ofthe fabric is positioned to engage the perforated drum and the uncoverednap side is to receive a stencil thereover while the rubber coveredportions of the nap side prevents the discharge of ink from the drum atthose portions.

Other and further important objects and advantages will become apparentfrom the disclosures in the following specification and accompanyingdrawings.

IN THE DRAWINGS FIG. 1 is a perspective view detail of a perforated drumover which the overlay or covering of this invention is applied.

FIG. 2 is a front elevational view of the covering of this invention.

FIG. 3 is a sectional view of the covering taken on the line 33 of FIG.2.

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 2.

FIG. 5 is a sectional view taken transversely through a perforated drumas shown in FIG. 1 with the covering of this invention mounted thereon.

AS SHOWN IN THE DRAWINGS The reference numeral 10 indicates generally aprinting drum such as used in mimeograph type stencil duplicators. Inkfrom a supply within the drum is thrown centrifugally outwardly throughclosely spaced apart small holes or perforations 11 in the outercylindrical surface of the drum. As will later be described a precutstencil is mounted over the perforated drum 10 to impart a printing topaper being fed therepast. The drum 10 includes an end wall 12, a driveshaft 13 about which the drum is rotated, a capped fill tube 14 in theend wall 12 for ink filling, and a rocking clamp 15 which extends acrossthe drum to removably receive a cloth cover and an overlying stencil.The clamp 15 is primarily for the stencil but it is generally arrangedto be positioned over the tops of both the cover and the stencil whenthey are extended around the drum.

A cover, designated generally as 16, is the basic subject matter of thisinvention. The cover comprises a porous cloth or fabric base 17 which isgenerally rectangular in shape. The porous cloth 17 may be a singlelayer or may comprise multiple layers. The cloth is preferably made ofcotton or a composite of one or more of the same or different fibers.The cloth is sufficiently wide to span the width of the drum and issufficiently long to make a complete covering of the apertured portionof the outer cylindrical surface of the drum. Across the top of thecloth is a metal clip 18 which is firmly crimped over and around thecloth end to securely hold the clip to the cloth. Similarly across thebottom of the cloth is another metal clip 19 which is again crimpedlyattached to the cloth. The cloth is one which preferably has a smoothsurface 20 on one sideand a nappy or rough surface 21 on the other side.It is the smooth side 20 of the cloth which is wrapped around and liesagainst the surface of the drum thus covering the apertures 11.

As stated above it is an object of this invention to per mit one largesize stencil duplicator to be used for the printing of many smaller sizestencils. This is accomplished by the cover or overlay member 16. An inkimpervious coating of a particular shape is fastened to selectedportions of the cloth cover to bar the passage of ink through thoseportions. The coating may be any one of many materials such as rubber orsynthetic rubber and hereinafter the use of the word rubber shall meaneither a natural rubber or a synthetic rubber. The rubber coating 22 ispreferably vulcanized or otherwise fastened to the nap side 21 of thecloth 17 over the cer tain selected areas thereof for the purpose ofaccomplishing an ink dam or bar to ink passage at those portions. Inconstructing the covering the rubber coating is applied to the nap sideof the porous base cloth for the purpose of gaining better adherence ofthe rubber to the cloth. 1n the vulcanizing process the rubber coatingis brought to sufficient heat to cause a bonding of the rubber to thenap of the porous base cloth. The heat applied is approximately 310 F.under pressure for about five minutes. The rubber coating 22 acts to define a smaller rectangular area 23 which has no ink impervious coatingand which constitutes the area over which a stencil is placed forultimate printing of the contents thereof. The size of the stencil to beprinted determines the size of the rectangular uncovered area. A numberof such covers may be optionally used with a single size drum toaccommodate the printing of numerous size stencils.

As best shown in FIG. 5 a supply of ink 24 is shown within the reservoirof the drum 10. The cover 16 has its top end held by the ends of itsmetal clip 18 to the end walls of the drum. The cover extends across thedrum under the spring clamp 15. Coiled extension springs 25 and 26 areattached to spaced positions on the covers lower end metal clip 19.Spaced apart pins 27 and 28 are fixedly mounted in a cut-out portion 29of the drum in a manner to project axially inwardly from the ends of thedrum. The free ends of extension springs 25 and 26 are hooked over thesespaced apart pins 27 and 28 to thus securely hold the cover 16 snugglyagainst the drum surface over its full area. The covering 16 performsthree functions, that of acting as a cushion for a stencil 30 to beplaced thereover, that of covering the ink apertures and thus dispersingthe ink over the full surface rather than at just the point of theapertures, and that of blocking the passage of ink at those portionsbeyond the outer perimeter of the stencil to be used for printing. Thestencil 30 is held to the drum in its position over the covering 16 bythe rockable spring clamp 15. In the drum presently used the clamp isplaced slightly inwardly of the outer surface of the drum so there is noprojection beyond the cylindrical surface even with the covering and thestencil under the clamp. The uncoated area of the covering is generallyplaced close to the top thereof so that the clamp 15 may be used to holdthe stencil.

The rubber coating 22 has been depicted in the drawing as havingsubstantial thickness beyond the thickness of the fabric. This showingof thickness has been accentuated in order to clearly show all theelements. However, in actual practice the rubber and fabric are weldedinto one piece with the rubber penetrating into and around the fabricthreads on the nap side so that the overall thickness is substantiallythe same. FIGS. 3 and 5 show sharp offsets in thickness where thestencil is to be placed whereas in fact the differential in thicknessesis very small so the stencil is permitted to lay flat thereover withoutbeing bent around corners at the position of the uncoated portion.

In the operation of a duplicator the rubber coated cloth covering 16 hasits top end clip 18 held by its ends in the opposing end walls of thedrum. The intermediate portion of the end clip 18 is disposed under thetransverse drum clamp 15 in a manner to have the smooth side 20 of thecloth wrapped against the apertures 11 of the cylindrical drum. Thebottom end clip 19 of the covering 16 is yieldably held by the springs25 and 26 to the pins 27 and 28 respectively in a manner to have thecovering taut and lying snuggly against the surface of the drum. Theprecut stencil 30 is then inserted in the clamp 15 over a portion of thecovering 16 so that the cut indicia lies over the uncoated rectangle 23of the covering 16. As paper to be printed is pressed against therotating drum 10 the stencil indicia is transferred to the paper byreason of the ink 24 moving outwardly through the apertures 11, throughthe uncoated portion of the cloth cover, and finally through the cutindicia in the stencil to reproduce the stencil matter on the paper.

Various details of construction may be changed without departing fromthe principles disclosed herein and we therefore do not propose limitingthe patent granted hereon otherwise than as necessitated by the appendedclaims.

What is claimed is:

1. In combination an ink holding drum for a mimeograph type of stencilduplicator having a substantial portion of its cylindrical surfaceprovided with a plurality of closely adjacent perforations constitutingan ink dispensing screen, and a covering removably mounted overtheentire screen portion of said drum, said covering comprising a porousbase cloth, an ink impervious rubber coating covering selected portionsof the outer surface of said porous base cloth to effect a damming ofink within the drum over those selected portions, and the remainingportions of the porous base cloth being uncoated and constitutingnon-dammed portions, 21 stencil to be reproduced placed over thenondammed portions of the porous base cloth, said rubber coatingvulcanized to said porous base cloth, and said porous base cloth havinga smooth surface on the side adjacent the drum and a nap surface on itsouter side to which the rubber coating is vulcanized.

1. In combination an ink holding drum for a mimeograph type of stencilduplicator having a substantial portion of its cylindrical surfaceprovided with a plurality of closely adjacent perforations constitutingan ink dispensing screen, and a covering removably mounted over theentire screen portion of said drum, said covering comprising a porousbase cloth, an ink impervious rubber coating covering selected portionsof the outer surface of said porous base cloth to effect a damming ofink within the drum over those selected portions, and the remainingportions of the porous base cloth being uncoated and constitutingnon-dammed portions, a stencil to be reproduced placed over thenon-dammed portions of the porous base cloth, said rubber coatingvulcanized to said porous base cloth, and said porous base cloth havinga smooth surface on the side adjacent the drum and a nap surface on itsouter side to which the rubber coating is vulcanized.